"Bottom trawling by fishermen, long believed to harm marine life, may be even more damaging than previously thought, affecting the seabed as seriously as intensive ploughing of farmland erodes the soil, according to a new Spanish study."

"Bottom trawling - dragging nets across the sea floor to scoop up fish - stirs up the sediment lying on the seabed, displaces or harms some marine species, causes pollutants to mix into plankton and move into the food chain and creates harmful algae blooms or oxygen-deficient dead zones.

Scientists from the Marine Sciences Institute in Barcelona and the University of Barcelona found that trawling displaced sea floor sediment and made the seabed smoother over time."